Generally, in a case of producing a master of optical discs, such as CD (Compact Disk), MD (Mini Disk), DVD (Digital Versatile Disk) and the like, in order to assure recording and reproducing of digital information, error correction and modulation are performed on predetermined information data to be recorded. FIG. 5 is a structural view of a conventional optical disc master producing system. This is a disc master producing system for CD. In the case of CD, so-called EFM (Eight-to-Fourteen Modulation) signal system is adopted.
Predetermined information data to be recorded in an optical disc master 320 is recorded in an master optical disc 310. In an EFM signal generator 400 being a modulated signal generator, a reader drive 410 reads out the information data recorded in the master optical disc 310 and transfers the data to a first signal processor 420. The first signal processor 420 sends the received information data to a second signal processor 430 and instructs a modulation process required to be performed. The second signal processor 430 comprises dedicated ICs or hardware logics, which comprises an ECC (Error Correction Code) /EDC (Error Detection Code) scrambling unit 431, a CIRC (Cross Interleave Reed-Solomon Code) unit 432 and an 9–14 conversion DSV (Digital Sum Value) unit 434 or the like. The second signal processor 430 carries out necessary signal processing on original data transferred from the first signal processor 420 and outputs a modulated signal to an EFM outputting unit 440. The second signal processor 430 carries out signal processing such as ECC generation, EDC generation, data scrambling, CIRC generation, Eight-to-Fourteen conversion, CD sub-code generation, optimization of DSV and interleave processing. The signal modulated by the second signal processor 430 is transferred to a laser beam recorder 200 via the EFM outputting unit 440 so that the optical disc master 320 is produced.
However, the conventional modulated signal generator has a problem that a speed of signal processing and a format to be supported cannot be easily changed. In recent years, the time required for producing an optical disc master has been shortened by having a shorter oscillation interval of a lser beam irradiated from the laser beam recorder 200 as well as having a higher rotation speed of the optical disc master 320 to be cut. For this purpose, it is required that signal modulation is processed at a higher speed. However, since the conventional modulated signal generator carries out the signal processing using the dedicated IC and the hardware logics, it has been necessary to have another dedicated IC for changing an output interval of the modulated signal. Faster signal processing has not been easily realized since it requires a considerable length of time and cost for developing a new dedicated IC.
In addition, in recent years a variety of techniques of adding predetermined information to a moduulated signal by setting a special format for the modulated signal have been suggested. For example, there is a technique to incorporate additional information into the modulated signal for a purpose of preventing illegal copying of the optical disc. Furthermore, there is a need for supporting new formats such as the one in which a recording density of a CD is made twice as a conventional CD. However, in a conventional modulated signal generator, the format which the generator supports is fixed and it is not easy to change the format.